Answer:
To create your histogram you could use the following intervals and frequencies.
5-9 (4)
10-14 (3)
15-19 (5)
20-24 (3)
You would create a frequency on your y-axis that goes to 5. Make sure the bars are touching each other because the data is consecutive (in order).
Label your x-axis #of customers.
Label y-axis frequency
Title: How many customers are shopping at lunch time?